Metal fiber bundles can be obtained in various ways. Metal fibers can be obtained by a method of bundled drawing as described e.g. U.S. Pat. No. 3,379,000. Metal fibers can also be obtained e.g. by drawing till final diameter, also called end drawing. Typically, metal fibers are less than 60 μm in equivalent diameter. A metal fiber bundle is generally characterised as an array of parallel metal fibers. One type of metal fiber bundles include continuous metal fibers e.g. as obtained by bundled drawing or end drawing and combining these metal fibers into a bundle. Such metal fiber bundles can then be combined to produce metal fiber yarns. These yarns have properties such as a determined strength and electrical resistance.
To increase the strength of a metal fiber yarn with continuous metal fibers of a certain thickness, more metal fibers need to be in the yarn. This can be done in two ways: by increasing the amount of metal fibers in the bundles or by increasing the amount of metal fiber bundles in the yarn.
Increasing the amount of metal fibers per bundle in the yarn has, however, a negative effect on the flexibility of the metal fiber yarn.
The smaller than expected increase in breaking load of the yarns consisting out of 5 or more metal fiber bundles occurring together with an increase in the sleeving phenomenon, made people in the art conclude that using 5 or more metal fiber bundles in a yarn was not favourable.
Accordingly, this invention seeks to provide metal fiber yarns with higher flexibility and flexlife. In a further elaboration of this invention, metal fiber yarns are provided with increased strength and processability.